High tension insulator



March 29, 1932.

HIGH TENSION INSULATOR Filed April a, 192e Patented Mar. 29, 1932 UNITEDSTATES NT ICE ROBERT M. JOHNSTON .AND ALNDER MCLACELAN, F HUNTINGTON,WEST VIRGINIA HIGH TENSION INSULATGR Application filed April 8, 1926.Serial No. 100,597.

This invention is a high tension insulator of the suspension type.

One of the objects of the invention is to provide a suspension typeinsulator for high tension strains, and for high unit electric valuescapable of use on superpower high voltage lines. A further object is toprovide an insulator of the character mentioned, possessing mechanicalstrength, and constructed w to give a maximum flash-over Value for anygiven diameter of insulator. A further object is to provide an insulatorso constructed that arcs are kept away from the hardware and cascadingfrom metal to metal is prevented. A further object is to provide aninsulator of the type referred to in which the hardware is united to thedielectric body by means of materials which cooperate to preventcracking of the porcelain due to any excess expansion of the metalsuspension pin. A further object is to unite a suspension cap :to thedielectric body in such a manner that said cap will back up andreenforce the porcelain, and resist bursting or splitting strains whichmay be imposed by undue expansion of an embedded metal suspension pin. Afurther object is to provide an insulator in which the metal anddielectric elements are united by means of metals or metal alloys whichmay be applied while in a molten state,

'and to protect the hardware and the metal anchoring materials by meansof waterproof ing material capable of withstanding the effects ofatmospheric moisture, and possessing sufciently high insulatingqualities to effectively reduce corona discharge under electric stress.

In the accompanying drawings Figure 1 is a cross sectional Viewillustrat- 40 ing an insulator constructed in accordance with theinvention. Figure 2 is a side elevation, partly in section, illustratinga modiiication.

Referring to Figure 1 of the drawings, 10 designates an insulator bodyconstructed of suitable dielectric material, preferably porcelain,provided with a hub-like portion 11, of any desired contour, anapproximately spherical shape having been selected for purposes ofillustration. |Thelbody is also provided with a flange or petticoat 12,having depending annular ribs 13, to increase the leakage and flash-overdistances. Said body is also provided with a central chamber 14, open atone end, as shown.

The hub-like portion- 11 is enclosed within l a correspondingly shapedcap 15, preferably of pressed steel, the internal diameter of said capbeing somewhat larger than the external diameter of the hub-like portion11. The edge or mouth of said cap is fiared outwardly asindicated at 16,the inner surface of said flared portion being provided with horizon`tally disposed annular ribs 17. The space between the cap 15 and the hubportion 11, except in the vicinity of the iared portion 16, is filled,as indicated at 18, with an asphaltum water-prooing material. interposedbetween the mouth portion of the cap and the contiguous portion of thedielectric body and interlocking with the ribs 17 is an anchorage 19,consisting preferably of an alloy of lead and antimony, which may beapplied while in a molten condition. Said alloy possesses thecharacteristic that upon cooling it will slightly expand, or at leastwill not shrink. An alloy of lead with fifteen percent of antimony haspractically no shrinkage and a higher percentage of antimony swells oncooling. For this reason, it is preferred to use an alloy consisting ofnot less than sixteen percent of antimony or more than eighty-fourpercent of lead.- The cap 15A is provided with a clevis 20, by means ofwhich the insulator may be suspended from a suitable support 0r fromanother superposed in sulator, in a well known manner.

Extending into the chamber 14 is a suspension pin 21, having its innerend enlarged to provide a head 22, the inner end of said chamber beingcorrespondingly enlarged contiguous to said head.' Said pin is reltained in the said chamber by means of an Y which do not affect it forthe purposes of the present invention. It will be observed that theanchoring metal extends laterally or radially into the enlarged innerend of the chamber 14 and beneath the lower edge of the head 22, so asto surround a portion of the shank of the p-in 21 and firmly retain itin place. Said anchoring metal 23 is covered to a substantial depth by abody of waterproofing material 24, similar to the material 18. The lowerend of the pin 21 is shaped to extend between the arms of a clevis 20 ofa lower insulator, or to engage a conductor support, in a manner wellunderstood in the art.

Referring to Figure 2 of the drawings, 30 designates an insulator bodypreferably constructed of porcelain, and provided with a centraldepending` portion 31, of approximately spherical shape. The body 30 isalso provided with a petticoat 32, of substantial depth, extending 'downand enclosing the dependin portion 31. 1f desired the dash-over and leaage distances of the insulator may be greatly increased by providing thepetticoat with annular ribs 33, 34, 35, 36 and 37,

as shown.

The body 30 is provided with a central recess or aperture 40, extendinginwardly from thetop to receive the shank 41 of a clevis pinenlarged-fatits lower end as indicated at 42, and provided at its upperend with a clevis 43. Interposed between the inner end of the pin andthe. adjacent surface of the dielectric material is a body 44 ofcushioning material, located in the bottom of the recess. Said pin issecured in position by means of an anchoring material 23a, preferably analloy of zinc or pure zinc, similar to the anchorage metal 23 of Figure1, the surrounding portion of the wall of the aperture 40 having annularanchoring ribs, as shown. The exposed portion of the alloy 23a iscovered by a body 24a of water proofing Vmaterial of substantial depthsimilar to the material 24 of Figure 1.

The approximately spherical portion 31 of the insulator body is enclosedwithin a correspondingly shaped cap 50 of metal, such as pressed steel,said cap being shaped to provide a centrally disposed coupling tongue51, having an opening 52 for'the clevis bolt carried by the clevis 43 ofan adjacent insulator unit. Said tongue is sticned by suitable webs 53.The open edge of the cap 50 extends into the narrow recess formedbetween the body portion 31 and the petticoat 32 and covers the bodyportion 31. Said cap is united to the body 31 by means of a-body ofalloy material indicates at 19a, having the same characteristics as thealloy 19 of Figure 1.

Extending from the edge of the cap, and between said edge and the end ofthe recess 54 is a body of elastic cushioning material 44a, similar tothat previously described Said elastic material is covered by a body 241of water-'proofing material similar to that already described, and alayer 181a of similar water-proofing material is also introduced betweenthe cap 50 and the body portion 31, extending downwardly from the alloy23D.' The wall of the cap adjacent its mouth is provided with internalannular ribs, as shown.

The advantages of the invention will be readily understood by thoseskilled in the art to which it belongs. It will be noted that the sameprovides a suspension type insulator for high tension strains, and forhigh unit electric values, such as is required for high voltage lines ofthe super-power type. An important advantage is that the high mechanicalstrength permits heavy conductors to be strung under high tension andwithout double yoking i. e. two strings yoked in parallel. v

Very important advantages are gained by the use of the anchoringmaterials which may be applied while in a molten state and possessingthe described characteristics relative to shrinkage upon cooling. Forinstance, it is well known that the compressive strength of porcelain ismuch greater than its tensile or bursting strength, due to the nature ofporcelain and the shapes employed. Therefore, an expanding alloy betweenthe cap and the porcelain places a stress upon the cap which willprevent bursting of the porcelain under the expected conditions ofservice. At the same time a shrinking alloy betweenthe pin and theporcelain provides a relief against bursting stress due to expansion ofthe metal pin by heat. Therefore, the employment of a material 23 whichwill shrink slightly upon cooling, will prevent cracking of theporcelain due to any strains set up by an excessive expansion of themetal pin 24 at the high temperatures frequently encountered in service,because said material 23 will act as a cushion and take up said strainsbefore they can have any destuctive eii'ect upon the porcelain. Byemploying an anchoring material for the cap, which material has thecharacteristic that it will swell slightly upon cooling, a tensionbetween the cap and the porcelain is assured, which will back up andreenforce the porcelain to such extent that it will resist the burstingor splitting strains normally im# posed by the enlarged head of the pin21. The use of the water prooiing material serves to seal all holesthrough which the molten material is poured and ills all of the airspaces so as to prevent coronadischarge under electric stress. At thesame time the hardware is also well protected from water and corrosion.

Having thus explained the nature of the invention and described anoperative manner of constructing and using the same, although withoutattempting to set forth all of the forms in which it may be made, or allof the forms of its use, what is claimed is 1. An insulator of thecharacter described comprising a body of dielectric material having ahub portion and an internal chamber extending centrally into said hubportion, a metal cap complemental to said hub portion, a compensatorinterposed between the edge of said cap and said hub-like portion, saidcompensator consisting of a metal capable of expanding after beingplaced in position, a pin having a portion extended into said chamber, acompensator for excessive expansion of said pin, said compensatorconsisting of a metal anchoring material located within said chamber andsurrounding the adjacent end -portion of said pin, said last mentionedmetal possessing the characteristic of shrinking after being placed inposition.

2. An insulator of the character described comprising a body ofdielectric material having a hub-like portion andan internal chamber, ametal cap complemental to said hublike portion, a compensator interposedbetween the edge of said cap and the adjacent surface of said hub-likeportion, said comantimony capable of being applied while in a moltencondition, and capable of expanding upon cooling a pin having an endextended into said chamber,a compensator for excessive expansion ofsaidpin, said compensator consisting of zinc capable of being'applied in amolten condition, said zinc substantially filling the cross section ofthe closed end of said chamber and engaging the end of said pin.

3. An insulator of the character described comprising a body ofdielectric material having a hub-like portion of approximately sphericalshape and a petticoat iange, said body of dielectric material beingprovided with an axially disposed chamber, a capfhaving an edge restingon said iange, said cap being thickened adjacentto said edge, acompelsatcr interposed between said edge and the adjacent surface ofsaid spherical portion,

said compensator consisting of a metal capable of expanding after beingplaced in position, a iilling of water proof material interp osedbetween the cap and the hub-like portlon above the irst mentionedcompensator, a pin inserted in said chamber, a compensator pensatorconsisting of an alloy of lead and las

